Grinder



Dec. 23, 1958 CJSHUMWAY 2,865,140

GRINDER Filed Dec. 29, 1955 4 Sheets-Sheet 1 H||l|- INVENTOR. md SAM/77 we A T 7K1 Dec. 23, 1958 Filed Dec. 29, 1955 C. SHUMWAY GRINDER 4 Sheets-Sheet 2 IN V EN TOR.

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GRINDER Filed Dec. 29, 1955 4 Sheets-Sheet 4 117 3 30 INVENTOR.

United States Patent "ice I GRINDER Conrad Shumway, Manlius, N. Y. Application December 29, 1955, Serial No. 556,253

18 Claims. (CI. 51-34) Thefpresent invention relates to a knife grinder particularly designed for grinding theknives used in wood chippers.

An object of the invention is to provide a grinder for a plurality of such knives which will be ground exactly alike and at the same time.

A further object of the invention is to provide a grinder which will grind a perfect set of knives for a wood chipper having the desired helicoidal surface to match the helicoidal surface of the disc segments.

A further object of the invention is to provide a clampingrack for the knives capable of maintaining the knife edges at thedesired angle for grinding and capable of being adjusted so that, the proper helicoidal surface is ground.

A further object of the invention is to provide an apparatus which will produce at a single grinding a uniform modified helicoidal surface with the correct helix angle at each end upon all the knives of a set.

A still further object ofthe invention is to provide a grinding wheel frame wherein the desired rotating and reciprocating motion may be given to the. grinding wheel.

A stillfurther object of the invention is to provide a frame construction for the grinding wheel so that the axis thereof may always beperpendicular to the sharp edge of theknives.

A still further object of the invention is to provide a frame wherein the tracks for the grinding wheel are set at a horizontal angle to'the sharp edge of the knives so that as the rotating wheel is carried alongthe length of the knives it is also drawn across the edges of theknives. A still-further object of the invention is toprovide a clamping rack wherein the knives are slightly rotated in relation to one another without any bending or distortion ofthe'knives so that a-helicoidal surface may be ground thereon. When 'the' grinding wheel is carried along the knives insuch case its axis is caused to rotate slightly by the different vertical angles of the tracks which will result in grinding all the knives .of the set exactly alike with the correct helix angle at'each end. With the above and other .objects 'in view which will become apparent from the detailed description below, a preferred embodiment of the invention is shown in the drawings inwhichz.

Figure 1 is a side view of the grinder;

Figure 2 is a front view;

Figure} is a top plan view;

' Figure 4 is a perspective view of the grinding wheel and a set of knives illustrating diagrammatically the principles involved in the new grinder;

Figure 5 is a top plan veiw of the clamping rack;

Figure 6 is a sideview of the clampingrack and Figure 7 is a partial front view of the clamping rack showing particularly the construction at one of the ends thereof. t

- In the various figures similar reference characters indicatelikeparts.

In the Normantype wood chipper as shown in Patent Z,8ii5,l40 Patented Dec. 23, 1958 No. 2,183,224 granted December 12, 1939 to S. Norman and which is used in the paper industry to reduce pulp Wood stock to chips for processing into acid pulp paper stock known as sulphite there are several advantages over other wood chippers. These advantages include the production of a more uniform chip with less waste of stock as dust and slivers and an economy of the power necessary. An important feature of the Norman t-ype chipper is the helicoidal surface of the bits instead of the flat surface of the revolving disc in other chippers in which the radial knives are set. The pulp wood stock is therefore drawn into the chipper in the same manner that an anger is drawn into a timber.

A bit in the Norman type wood chipper has a knife edge and a helicoidal surface between such knife edge and the following knife edge. This helicoidal surface is bounded by four lines. First the knife edge itself which isa straight line. Second, another straight line parallel to the next following knife but below at a distance equal to the pitch or bite which will produce the required chip length; Third, the curved line on the helix joining the outer ends of the above mentioned lines and fourth, another curved line on the helix joining the inner ends of the above straight lines. Thus the surface is curved along any chord but not along any radius included in this area. The trailing edge of the ground surface of the knife can be assumed to be a straight radial line and since the knife or bit is only a half inch thick and the ground surface less than /8 of an inch in width the curvature of the ground surface can be regarded as negligible. The new grinder will produce on a set of knives, at a single grinding, a uniform modified helicoidal surface with the correct helix angles at the ends of each knife.

Referring to Figure 4, which illustrates diagrammatically important features of the grinding, there is shown at A a grinding wheel and at B a set of knives held in the rack C. The knives B are positioned in the rack so one side of the rack C is disposed at'an angle of 1' from the horizontal while the other side is positioned at an angle of 3 from the horizontal. These angles may be varied as desired, depending upon the chip length and number of knives for which the chipper is designed.

A'construction making use of the above principles will now be described with particular reference to Figures 1, 2 and 3.

The grinder ismounted upon a base 5 from the top surface of which extend the four standards 6. Pivotally mounted upon the standards 6 is a frame member indicated generally at 7 and this frame member comprises the side bars 8 and the racks 9. The frame member 7 is pivoted upon'the tworear' standards 6 at 10 in any desired manner. I

Mounted upon the frame by means of the pillow blocks ll is a grinding wheel '12 driven by'the motor 14. The shaft-15 of the grinding wheel is connected through a reduction gearing with the motor 14. The reduction gearing is located within the casing 16. The shaft 15 also has connected thereto gears at each side of the grindingwheel which are located within the pillow blocks 11 and travel'upon the racks 9 which serve as tracks. The tracks 9 are set at a slight inclination to the horizontal axis of the machine.

The motor 14 is provided with any desired type of reversing mechanism so that as the grinding wheel reaches the end of its stroke in one direction it is reversed and travels in :the other-direction; Any suitable mechanism ments may be located at the side bars 8. The frame/7 may be tilted as shown in dotted lines in Figure 1 and the motor 14 serves as a counterbalance for this pivoting. The front ends of the side bars 8 are provided with downwardly extending projections 17 which extend into slots 18 provided upon the front standards 6. Extending through the projections 17 and the standards 6 are aligned bores in order to receive the bolts and wing nuts 19 which will lock the frame 7 in operative position.

Below the frame there is provided a platform 20 which can be raised and lowered 'by means of the threaded pillar 21. A gear 22 is threaded upon the pillar 2.1 and is actuated by a worm gear 23 fixed upon a shaft 24. The shaft 24 may be manually rotated by the Wheel 25 located at the front of the machine. The rods 26 fixed upon the top of the base serve as guides for the platform 2'8 in its adjustment upwardly or downwardly.

Mounted upon the platform 26 is the clamping rack, indicated generally at 28, which clamps the knives 29 in the requisite position for proper grinding by the wheel 12.

The details of the clamping rack are shown in Figures 5, 6 and 7. The knives 29 are positioned upon the knife seats 30 which are spaced from one another by the washers 31. At each side of the set of knives clamping members 32a and 32b operable by means of the hand wheels 33 are provided. Each clamp 32 consists of two parts, a fixed part 32a and a movable part 3211. The movement of the latter is limited by two shoulder screws 34, and is caused by the threaded rod 35, which is turned by the handwheel 33. Two coil springs 36 and 37, in recesses in the parts of 32, help open the clamp when it is released by the handwheel 33. Guide rods 38 are provided to line up the ends of the knives before they are clamped. Each guide rod fits into recesses in parts 32a and 32b, and bears against coil spring 37. A wingheaded bolt 39 is provided to drive one end of the guide rod sidewise against two coil springs 40 and thus secure the knives endwise, the recess for that end of the rod being slotted, rather than round, to allow this movement. Two openings 41 are cut in the top of each knife seat to allow the use of slings in carrying the set of knives. If wedge shape strips 42 are fastened between 32a and 32b, tapered at approximately 1 at the right end of the knife seats and at approximately 3 at the left end, there will be a slight rotation of the knives in relation to each other, so that a helicoidal surface is ground on the knives. The exact amount of taper is determined by the length of the chip and the number of knives for which the chipper was designed.

It is believed that the operation of the grinder is clear from the above description. The set of knives from a chipper are held in the sling and are then disposed upon the knife seats 30. The rack is then clamped upon the knives by means of the handwheels 33. For the insertion of the knives the frame 8 has been pivoted to the dotted line position shown in Figure 1 and after the knives have been placed in position the frame is locked in position above the knives by means of the bolt and wing nut 19. The motor 14 is then started and the grinding wheel rotates and reciprocates above the cutting edges of the knives. At the same time the grinding Wheel, due to the inclination of the tracks 9, will move slightly transversely to the cutting edges.

It is thought that the invention and its advantages will be understood from the foregoing description and it is apparent that various changes may be made in the process, form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing its material advantages, the form hereinbefore described and illustrated in the drawings being merely a preferred embodiment thereof.

Iclaim:

1. A knife grinder comprising a rack, means for clamping a plurality of knives in said rack with each knife at a slightly different angle longitudinally to the hori- Zontal, a frame located above said rack, a cylindrical grinding wheel mounted in said frame and means for rotating and reciprocally moving said wheel above said knives so as to grind a modified surface upon all of said knives.

2. A knife grinder comprising a rack, means for clamping a plurality of knives in .said rack with each knife longitudinally maintained at a different vertical angle, a frame mounted above said rack, grinding means mounted in said frame, means for operating said grinding means and means for reciprocating said grinding means across said knives when so clamped.

3. A knife grinder comprising a rack, means for clamping a plurality of knives in said rack with each knife clamped at a slightly different vertical angle, a frame located above said rack and pivoted at one end thereto, said frame extending at a slight inclination to said rack, a grinding wheel mounted in said frame, means for rotating said grinding wheel and means for moving said grinding wheel so as to grind a uniform modified surface upon each of said knives having the correct helix angle at each end upon all of said knives.

4. A knife grinder comprising a rack, means for clamp ing a plurality of knives in said rack with each knife clamped at a slightly different vertical angle, a frame located above said rack and pivoted at one end thereto, said frame extending at a slight inclination to said rack, grinding means mounted in said frame, means for operating said grinding means, means for reciprocating said grinding means to grind a modified surface upon each of said knives having the correct helix angle at each end.

5. A knife grinder as set forth in claim 4 wherein means are provided whereby when said grinding means is carried along the length of the knives it is also drawn across the edges of said knives.

6. A knife grinder as set forth in claim 4 wherein said rack contains a plurality of inclined knife seats spaced from one another.

7. A knife grinder as set forth in claim 4 wherein said rack comprises a fixed portion and a movable portion for clamping said knives against said fixed portion.

8. A knife grinder as set forth in claim 4 wherein means are provided at the free end of said frame for locking said frame in position above said knives.

9. A knife grinder as set forth in claim 4 wherein means are provided for adjusting the vertical height of said rack.

10. A knife grinder as set forth in claim 4 wherein means are provided in said rack for aligning said knives at the ends thereof.

11. A knife grinder as set forth in claim 4 wherein a wedge shaped strip is positioned in said'rack at one side thereof for varying the inclination of the cutting edge of each of said knives with .respect to :one another.

1-2. A knife grinder as set forth in claim 4 wherein a tapered strip is located in said rack at each side thereof under the ends of said knives, said strips having a different angularity.

13. A method of grinding knives for wood 'chippers comprising positioning a plurality of knives each at a slight and different inclination to the horizontal along the longitudinal axes of said knives and then moving grinding means across the cutting edges of said knives to grind a uniform modified surface upon each of said knives having the correct helix angle at each end .upon all of said knives.

14. A method of grinding knives for wood chippers comprising clamping a plurality of knives each at a slight and different inclination to the horizontal along the longitudinal axes of said knives and each at a slight inclination to the vertical, .and then moving a grinding wheel across the cutting edges of said knives.

15. A method of grinding knives for wood chippers as set forth in claim 14 wherein said grinding means is also moved along the cutting edges of said knives.

16. A knife grinder comprising means for clamping a plurality of knives wherein each knife edge is located at a different angle to the vertical from the other knife edges and also each knife edge is located at a different angle horizontally from each other and means for grinding the cutting edges upon said knives when so held so as to secure a modified uniform surface upon the bevel of each knife.

' 17. A knife grinder as set forth in claim 1.6 wherein said means for grinding said cutting edges moves along said knife edges and also transversely thereof.

18. A knife grinder comprising a rack, means for clamping a plurality of knives in said rack, a frame located above said rack, a cylindrical grinding wheel mounted in said frame, means varying gradually the angle of contact between the surface of said wheel and said knives from one end of said knives to the other end, means for rotating said wheel and means for reciprocating said wheel so as to grind a uniform modified surface upon each of said knives when clamped in said rack having the correct helix angle at each end upon all of said knives.

References Cited in the file of this patent UNITED STATES PATENTS Re. 6,412 Howes May 4, 1875 1,669,989 Madsen May 15, 1928 1,778,132 Wegner Oct. 14, 1930 1,929,810 Edwards et al. Oct. 10, 1933 2,088,402 Borck July 27, 1937 2,291,255 Powell July 28, 1942 2,518,018 Jung Aug. 8, 1950 2,705,391 Spaulding et al. Apr. 5, 1955 FOREIGN PATENTS 25,666 Great Britain Dec. 6, 1898 115,059 Great Britain Sept. 19, 1917 

